Water heater



J. S. CONNER April 15, 1952 WATER HEATER Filed Sept. 6. 1949 COLD l/VL Er 7 /62 M01727 7 VJL 1/6 Illl'lllllll'l'llll 1171?. 11.4.1754}.-

. INVENTOR .1746! I. CON/V62.

ATTORNEY i a't'ented Apr. 15, i952 UNITED STATE-1S7 ear ENT oFFica w WATER HEATER s im; 5S; chilies-110s Ailgeies, .risisiiaataspttaters, 1949, sri'arivi1i iji were. (or. 122 13 I My invention relates to automatic 'rnfstic" water heaters of 'thefstorage typeand, more par ticularly; to'a meansrerreducing stratification in such" heaters *as'a"' result' ofjshortwithdrawaiswhen the'in'let water is"excessively'coldri In? general; domestic "water heaters utilize an; insulated" tank heated by gas or electricity I-ljot; \vateris' dr'awn fromithetopfot the'tan 'd isreplaced bycomwatei from thefmain througha dipftube enteringtheftop Qff thefta'n and e tn'ding nearly" to the bottom of thef tan H thermostat is positioned in the bottom offthe" tank adjacent the end of the diptube, 'ahd- -this teamma es: connected to control the tank heater} Usually a--sma1 1 hole "isbore'd iri-the '16" diptube near the wiser the'f tank to -"p're'vent back siphoningo'f the contents of thetank hen aiid' -if the'supp1ym'a'inds opened; thereby 'cau'sing loss of pressure. 7 g p v Such tanks function well'in maintaining-a de siredtemperature differential between top and bottofn'i'of the tank on short draws, when the temper ature of therr'iain'water is relativei'yhig'hi above 50 F, for example. However, in geographical locations experiencing extended cold weather; the'water 'in' the mains may drop-to a much'lower figure, in "some locations'as low as" 32 Underthese"conditions a water heater such as "above described does not function-prop erly when short withdrawals" are being made, and particularly when a series of such withdrawals is made.

The reason fon 'this'is that the incoming cold water slugs thethermostat so that its recovery time for shut-off of the heater is relatively long asrcompared tothe' timeof withdrawal so that the temperature at the top of the-tank rises, increasing the differential temperature between top and bottom of theta'nk; A "series of short withdrawalsmay add only a cupful or tw of cold water to-the tank. Hence,-if' such withdrawals are --c1ose togethen the 'heatei" may rein 5 on ccjn'ti'nuouslyg with-excessively cold inlet'wa er', it *not unknown for the -water 'a tthe topoii he ta nk to' equal or exceed 212 FL, thereby-causing the water to flash into steam at the faucet.

One means that has heretofore been utilized to prevent such excessive stratification and overheating is to place a second thermostat in the top of the tank to regulate the maximum temperature to which the tank water can rise. This solution to the problem is satisfactory except from an economy standpoint, as the extra thermostat involves a manufacturing cost of from $7.00 to $10.00 in ordinary household water heatdifferential;- My iriventicewrit make tne'inret 46 efence" to the drawings s d nth' a e-:typepr pus h isfequall'y satisfactorybut ditiOnE lf cost of af evv'c It 1 is a b ec ing m' d i i'se h m a mean x iessiveitem erat mostat domestic water-heat A .2311; withdrawals ti i essiv it i pi ra ur eat ri pilm saFa ries 0 39 regardlessjof the in18 to fil'ifiugth? adjacentthe top offth tank ofi ab ou with the r "comincold 'watery The-water *1 ing -the dip tubfefaiid actuatin will thefi' "be at'asubstarrtially hi water-temperature rise piisportionar to secrete increase" etween thetdp airdbottom-tank reinerature'sz k right type and, for example, of 30-gallon capacity. As is customary, the tank is surrounded by a layer of heat insulation 2. Hot water is withdrawn from the top 3 of the tank through outlet 4. Cold water enters the tank through a dip tube 5 connected to inlet pipe 6, the dip tube entering the tank I at once side of the top 3 and extending downwardly to within about eight to ten inches of the bottom I of the tank. A thermostat 8 is inserted into the tank I through the side thereof, extending, in most such heaters, to a point in the vicinity of the lower opening 9 of the dip tube 5.

The thermostat 8 is connected outside of the tank to a thermostat valve l0 which controls gas from a gas main H to a main heating burner l2. Burner [2 is also provided with a pilot l3 supplied through valve l0. As there is a multitude of ways by which heat from the burner can be applied to the water in the tank using inside or outside flues, no particular flue arrangement is shown, as the operation of the invention is not afiected by the vent. In like manner most domestic water heaters utilize a thermocouple control of the thermostat valve so that when the pilot flame goes out, the thermostat valve 10 cannot be opened. As this feature also in no way affects the present invention, it has not been shown.

In the dip tube 5, I provide an injector located adjacent the top of the tank, preferably about 2 inches below the top 3. I have found that a simple injector as shown in Figure 2 is satisfactory to inject about 10% of the top hot water in the tank into the dip tube when one household faucet is opened under a normal main of from 50 to 90 lbs. per square inch.

The injector 15 of the Bernoulli type is preferably formed by making opposite saw cuts 16 in the wall of the dip tube and then bending portions 11 of the dip tube above the cuts inwardly to form a venturi constricting the dip tube and at the same time forming water inlet orifices Hi. It has been found that the cost of such an injector is only a few cents. It should be noted here that no anti-siphon bore is needed in the dip tube when the injector is used therein, as the orifices l8 perform the same function.

During the passage of the cold water down the dip tube it becomes thoroughly mixed with the injected hot water, and the water discharged from the end opening 9 of the dip tube is appreciably warmer than the water in the mains, thereby preventing slugging of the thermostat even after successive short draws, and makin the heater behave exactly as if the cold water entering from the mains were to be significantly warmer. I have also found that the use of the injector as described is in no way detrimental to the operation of the device on long draws such as might be used for filling a washing machine or for showers, etc., and further does not interfere in the least with satisfactory performance of the heater when the inlet water is warmer.

While I have found that an injector mixing about 10% of hot tank water with the cold inlet water is satisfactory for most locations where the inlet water may become excessively cold, injectors using a greater or less proportion of the hot water may be used where inlet temperature conditions warrant such a change.

It is also to be understood that, while I have shown the present invention as applied to a gas fired water heater, it is equally effective when other heat sources are used requiring a thermostat inserted in or connected to the outside of the tank for temperature control.

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is susceptible of modification in its form, proportions, detail construction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages.

While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise the preferred form of putting the invention into efiect, and the invention is, therefore, claimed in any of its forms or modifications within the legitimate and valid scope of the appended claim.

I claim:

A cold water inlet for a storage type hot water heater comprising an elongated upright tank, a

cold water inlet dip tube entering the top of said tank and sealed thereto and extending downwardly directly exposed to the water of the tank to open adjacent the bottom of said tank, said clip tube adjacent the top of said tank being out along generally co-planar horizontal lines, with the sides of said dip tube being bent inwardly toward each other just above said cuts, thereby forming a constriction and two openings whereby hot water from the top of said tank is drawn into said dip tube by the Bernoulli efiect to raise the temperature of water entering said tank through said dip tube, said constriction and said openings being proportioned to mix about 10% of the water from the top of said tank with water entering said tank through said clip tube.

JACK S. CONNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,817,685 Graham Aug. 4, 1931 1,886,135 Tannehill Nov. 1, 1932 2,066,190 Swars Dec. 29, 1936 2,251,426 Schmid Aug. 5, 1941 2,348,901 I-Iandley May 16, 1944 

